1. The Field of the Invention
The present invention pertains to a method and apparatus for drilling and completing a well.
2. The Prior Art
Sand control systems, employing expandable screens, are often used for sand control in well completions. To date, it has only been possible to install them following drilling of the hole for installation. This takes time to execute and carries a risk that the hole may collapse following drilling but prior to screen installation.
U. S. Pat. No. 6,196,336 to Fincher et al describes a method and apparatus for drilling a borehole in underground formations with at least one formation that has a significantly different formation pressure than an adjacent formation or where time dependant unstable formations do not allow sufficient time to case off the hole in a subsequent run.
British Patent No. 2,357,101 to Hahn et al describes a method and apparatus for drilling wellbores by drilling a pilot wellbore and, with a trailing under reamer, enlarging the wellbore to the desired size. At least one steering section provides relatively precise directional control. An expandable liner may be used during the drilling process, which liner can be expanded in order to retrieve the drilling assembly while avoiding a secondary operation to expand the liner.
PCT Publication WO 00/61310 to Coon et al describes a method for manufacture of substantially cylindrical pipe at an on site workshop by rolling flat metal stock into a round section and sealing the seam between the stock edges.
PCT Publication WO 00/61915 to Coon et al describes a method for drilling a wellbore in an underground formation using a drilling tubular which is capable of being expanded in place. A radial load is applied to the tubular to expand it to line the borehole. Preferably a sealing material is pumped between the drilling tubular and the wellbore wall prior to expanding the drilling tubular.
A sand control system employing an expandable screen (mounted on either solid or slotted pipe) has an inner string to isolate the expandable screen. This allows for drilling fluids to be circulated to the bottom of the drilling assembly, before returning up the annulus as normal. Both the upper and lower parts of the expandable screen are mounted on the inner string by means of a swivel and seals. The swivel allows for drill string rotation (if needed), the seals ensure that drilling fluids do not circulate to the inside of the screen.
The inner string is integral with the internals of the bottomhole drilling assembly, allowing for retrieval of the BHA (bottomhole assembly), including a pilot bit. Upon retrieval an isolation valve will close and seal thus providing sand control integrity in the well.
Release from the sand screen will be by pumping a ball down the string and engaging this in a catcher to shift the sliding sleeve open, giving hydraulic access to the liner hanger and engaging slips (or other setting mechanism) in the previous casing. Further pressure will release the ball into a catcher, restoring communication through the drill string in case this is needed for well control or circulation purposes.
It is proposed to run an expandable sand control system (sand screens mounted on either solid or slotted pipe) on an inner drill pipe string. By having swivels and wall between the pipe and the screens, drilling fluids can be circulated to the bottom of the drilling assembly, before returning up the annulus as normal. The swivel also allows for rotation of the drill string, if needed. The drill string includes a bottomhole assembly comprising drill bit and associated tools. When the bottomhole assembly is at the required depth, the bottomhole assembly will be released from the sand screen by pumping a ball down the string and engaging in a suitable profile to shift the sliding sleeve open, giving hydraulic access to the liner hanger and engaging slips (or other setting mechanism) in the previous casing string. Further pressure will release the ball into a catcher, restoring communication through the drill string in case this is needed for well control or circulation purposes.
The bottomhole assembly can then be removed from the expandable screens, which have then been placed in the hole without risk of borehole collapse.
Expansion may then be carried out by conventional means (using compliant expansion tools) or by means of an expansion cone included in the bottomhole assembly behind the drill bit.
The subject expandable sand control system has an inner string to isolate a sand screen allowing for drilling fluids to be circulated to the bottom of the drilling assembly before returning up the annulus in the normal fashion. Both the upper and lower parts of the sand screen are mounted on the inner string by means of swivels and seals. The swivels allow for drill string rotation (if needed), the seals ensure that drilling fluids do not circulate to the inside of the screens. The inner string is integral with the internals of the bottomhole drilling assembly, allowing for retrieval thereof, including a pilot bit. An isolation valve will close and seal, upon retrieval, thus providing sand control integrity in the well. Release from the sand screen will be by pumping a ball down the string and engaging this in a catcher to slim the sliding sleeve open, giving hydraulic access to the liner hanger and engaging slips (or other setting mechanism) in the previous casing. Further pressure will release the ball into a catcher thereby restoring communication through the drill string for well control or circulation purposes.